Christina is 3/4 of Laura's age. In 7 years Christina will be 2 years older than Laura is now. How old is each

Question

Christina is 3/4 of Laura's age. In 7 years Christina will be 2 years older than Laura is now. How old is each

Answer 1

Hi Debbie,

 

 

A good set up is the starting point for these types of questions.

 

         Christina = 3/4 (Laura) 

 

So, in 7 years,

 

         Christina + 7 = Laura + 2 

 

*Notice that I put the "2" on Laura's side as Christina will be two years older than Laura* 

 

Now we solve this system of equations.

 

C = 3/4L

C+7=L+2

 

Using substitution to substitute 3/4L for C...

 

3/4L+7=L+2 

 

3/4L-L=2-7

 

-1/4L=-5

 

L=20 

 

If Laura is 20 now, Christina is 3/4(20) so 15. 

 

To check.

 

Christina in 7 years will be 22 years old. And that is 2 years older than Laura now since Laura is 20. 

 

 

Hope it helped.

 

Best,

Tae